The Critical Role of Contact Springs in Connectors

Contact springs play an essential role in connectors, with their functions primarily categorized into three key aspects:

1. Providing a Conductive Path for Electrical Signals The primary function of contact springs is to establish a conductive path for electrical signals between components. This can be efficiently achieved using common materials such as copper or copper alloys. While copper alloys have relatively low conductivity, typically 10% to 30% of pure copper’s conductivity, they are sufficient for most connector applications. However, for high-current or power distribution connectors, conductivity becomes increasingly critical. In such cases, materials with lower impedance are required to address issues related to Joule heating and micro-voltage drops, which can cause temperature rises.
2. Generating and Maintaining Contact Pressure The second function of contact springs is to generate and maintain contact pressure. This is more complex as it involves the interplay between material properties and design parameters. Contact springs are generally classified into two types:
   • Socket Springs: Typically elastic structures.
   • Plug Springs: Usually rigid structures designed to induce elastic deformation in socket springs, thereby generating normal force.
3. Facilitating Permanent Connections The third function of contact springs is to facilitate the formation of permanent connections. This requires a comprehensive consideration of material properties and achieving a balance among various demands. For separable contact interfaces, the elasticity of contact springs is crucial for providing normal force between the two mating surfaces. Young’s modulus and yield strength are the most significant material properties influencing this, as they determine elastic offset characteristics and offset magnitude. Stress relaxation resistance is also important, as it helps reduce mating and unmating forces.

Balancing Material and Manufacturing Performance

To achieve optimal performance, several trade-offs must be considered:

• Mechanical Strength vs. Manufacturability: Mechanical strength, typically measured by yield strength, is essential for providing elastic mating force at the interface. However, higher mechanical strength can limit the material’s formability and forgeability.
• Stress Relaxation vs. Mating Force: Stress relaxation resistance reduces mating force but requires careful material selection and design to ensure reliability.

Conclusion

The design and material selection of contact springs are critical to the performance of connectors. Whether it involves electrical or mechanical performance, achieving the right balance among conductivity, elasticity, stress relaxation resistance, and manufacturability is essential. By thoroughly analyzing the interaction between material properties and design parameters, high-performance connectors that meet diverse requirements can be developed.